In vitro maturation response of oocytes of the catfish Heteropneustes fossilis (Bloch) to salmon gonadotropin in ovary – head kidney co-culture

Ovarian tissue from gravid catfish, Heteropneustes fossilis, was cultured in the modified Wolf and Quimby medium either alone or in co-culture with homologous head kidney pieces. This system was used to study the effect of salmon gonadotropin (SG-G100) on oocyte maturation. Oocytes did not mature when ovarian tissue was cultured alone, while 19% of the oocytes underwent maturation in ovary – head kidney co-culture. Addition of SG-G100 (20 μg/ml) to the incubation medium containing ovarian tissue evoked maturation in 13% of the oocytes, whereas the same amount of SG-G100 added to ovary – head kidney co-culture increased the maturation response to 54%. These results suggest that SG-G100 can bring about significant in vitro maturation of oocytes only in the presence of the interrenal tissue.